Since the term atopic dermatitis was first introduced in 1933 by Wise and Sulzberger to emphasize the association of eczema with allergic rhinitis and asthma, there has been considerable controversy over the role of allergens in atopic dermatitis. Recent studies suggest that allergens do contribute to the pathogenesis of this disease in at least a subset of patients. An understanding of the immune mechanisms regulating IgE production and the pathogenic events that contribute to the clinical features of this illness may lead to new insights into potential modes of therapy in atopic dermatitis.